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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* relocate_kernel.S - put the kernel image in place to boot
* Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
*/
#include <linux/linkage.h>
#include <asm/page_types.h>
#include <asm/kexec.h>
#include <asm/nospec-branch.h>
#include <asm/processor-flags.h>
/*
* Must be relocatable PIC code callable as a C function, in particular
* there must be a plain RET and not jump to return thunk.
*/
#define PTR(x) (x << 2)
/*
* control_page + KEXEC_CONTROL_CODE_MAX_SIZE
* ~ control_page + PAGE_SIZE are used as data storage and stack for
* jumping back
*/
#define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset))
/* Minimal CPU state */
#define ESP DATA(0x0)
#define CR0 DATA(0x4)
#define CR3 DATA(0x8)
#define CR4 DATA(0xc)
/* other data */
#define CP_VA_CONTROL_PAGE DATA(0x10)
#define CP_PA_PGD DATA(0x14)
#define CP_PA_SWAP_PAGE DATA(0x18)
#define CP_PA_BACKUP_PAGES_MAP DATA(0x1c)
.text
SYM_CODE_START_NOALIGN(relocate_kernel)
/* Save the CPU context, used for jumping back */
pushl %ebx
pushl %esi
pushl %edi
pushl %ebp
pushf
movl 20+8(%esp), %ebp /* list of pages */
movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
movl %esp, ESP(%edi)
movl %cr0, %eax
movl %eax, CR0(%edi)
movl %cr3, %eax
movl %eax, CR3(%edi)
movl %cr4, %eax
movl %eax, CR4(%edi)
/* read the arguments and say goodbye to the stack */
movl 20+4(%esp), %ebx /* page_list */
movl 20+8(%esp), %ebp /* list of pages */
movl 20+12(%esp), %edx /* start address */
movl 20+16(%esp), %ecx /* cpu_has_pae */
movl 20+20(%esp), %esi /* preserve_context */
/* zero out flags, and disable interrupts */
pushl $0
popfl
/* save some information for jumping back */
movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
movl %edi, CP_VA_CONTROL_PAGE(%edi)
movl PTR(PA_PGD)(%ebp), %eax
movl %eax, CP_PA_PGD(%edi)
movl PTR(PA_SWAP_PAGE)(%ebp), %eax
movl %eax, CP_PA_SWAP_PAGE(%edi)
movl %ebx, CP_PA_BACKUP_PAGES_MAP(%edi)
/*
* get physical address of control page now
* this is impossible after page table switch
*/
movl PTR(PA_CONTROL_PAGE)(%ebp), %edi
/* switch to new set of page tables */
movl PTR(PA_PGD)(%ebp), %eax
movl %eax, %cr3
/* setup a new stack at the end of the physical control page */
lea PAGE_SIZE(%edi), %esp
/* jump to identity mapped page */
movl %edi, %eax
addl $(identity_mapped - relocate_kernel), %eax
pushl %eax
ANNOTATE_UNRET_SAFE
ret
int3
SYM_CODE_END(relocate_kernel)
SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
/* set return address to 0 if not preserving context */
pushl $0
/* store the start address on the stack */
pushl %edx
/*
* Set cr0 to a known state:
* - Paging disabled
* - Alignment check disabled
* - Write protect disabled
* - No task switch
* - Don't do FP software emulation.
* - Protected mode enabled
*/
movl %cr0, %eax
andl $~(X86_CR0_PG | X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %eax
orl $(X86_CR0_PE), %eax
movl %eax, %cr0
/* clear cr4 if applicable */
testl %ecx, %ecx
jz 1f
/*
* Set cr4 to a known state:
* Setting everything to zero seems safe.
*/
xorl %eax, %eax
movl %eax, %cr4
jmp 1f
1:
/* Flush the TLB (needed?) */
xorl %eax, %eax
movl %eax, %cr3
movl CP_PA_SWAP_PAGE(%edi), %eax
pushl %eax
pushl %ebx
call swap_pages
addl $8, %esp
/*
* To be certain of avoiding problems with self-modifying code
* I need to execute a serializing instruction here.
* So I flush the TLB, it's handy, and not processor dependent.
*/
xorl %eax, %eax
movl %eax, %cr3
/*
* set all of the registers to known values
* leave %esp alone
*/
testl %esi, %esi
jnz 1f
xorl %edi, %edi
xorl %eax, %eax
xorl %ebx, %ebx
xorl %ecx, %ecx
xorl %edx, %edx
xorl %esi, %esi
xorl %ebp, %ebp
ANNOTATE_UNRET_SAFE
ret
int3
1:
popl %edx
movl CP_PA_SWAP_PAGE(%edi), %esp
addl $PAGE_SIZE, %esp
2:
ANNOTATE_RETPOLINE_SAFE
call *%edx
/* get the re-entry point of the peer system */
movl 0(%esp), %ebp
call 1f
1:
popl %ebx
subl $(1b - relocate_kernel), %ebx
movl CP_VA_CONTROL_PAGE(%ebx), %edi
lea PAGE_SIZE(%ebx), %esp
movl CP_PA_SWAP_PAGE(%ebx), %eax
movl CP_PA_BACKUP_PAGES_MAP(%ebx), %edx
pushl %eax
pushl %edx
call swap_pages
addl $8, %esp
movl CP_PA_PGD(%ebx), %eax
movl %eax, %cr3
movl %cr0, %eax
orl $X86_CR0_PG, %eax
movl %eax, %cr0
lea PAGE_SIZE(%edi), %esp
movl %edi, %eax
addl $(virtual_mapped - relocate_kernel), %eax
pushl %eax
ANNOTATE_UNRET_SAFE
ret
int3
SYM_CODE_END(identity_mapped)
SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
movl CR4(%edi), %eax
movl %eax, %cr4
movl CR3(%edi), %eax
movl %eax, %cr3
movl CR0(%edi), %eax
movl %eax, %cr0
movl ESP(%edi), %esp
movl %ebp, %eax
popf
popl %ebp
popl %edi
popl %esi
popl %ebx
ANNOTATE_UNRET_SAFE
ret
int3
SYM_CODE_END(virtual_mapped)
/* Do the copies */
SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
movl 8(%esp), %edx
movl 4(%esp), %ecx
pushl %ebp
pushl %ebx
pushl %edi
pushl %esi
movl %ecx, %ebx
jmp 1f
0: /* top, read another word from the indirection page */
movl (%ebx), %ecx
addl $4, %ebx
1:
testb $0x1, %cl /* is it a destination page */
jz 2f
movl %ecx, %edi
andl $0xfffff000, %edi
jmp 0b
2:
testb $0x2, %cl /* is it an indirection page */
jz 2f
movl %ecx, %ebx
andl $0xfffff000, %ebx
jmp 0b
2:
testb $0x4, %cl /* is it the done indicator */
jz 2f
jmp 3f
2:
testb $0x8, %cl /* is it the source indicator */
jz 0b /* Ignore it otherwise */
movl %ecx, %esi /* For every source page do a copy */
andl $0xfffff000, %esi
movl %edi, %eax
movl %esi, %ebp
movl %edx, %edi
movl $1024, %ecx
rep ; movsl
movl %ebp, %edi
movl %eax, %esi
movl $1024, %ecx
rep ; movsl
movl %eax, %edi
movl %edx, %esi
movl $1024, %ecx
rep ; movsl
lea PAGE_SIZE(%ebp), %esi
jmp 0b
3:
popl %esi
popl %edi
popl %ebx
popl %ebp
ANNOTATE_UNRET_SAFE
ret
int3
SYM_CODE_END(swap_pages)
.globl kexec_control_code_size
.set kexec_control_code_size, . - relocate_kernel
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